Method of corrugating tubes



Jan. 21, 1936. w, H, GRANT 2,028,151

I METHOD OF CORRUGA'IING TUBES Original Filed April 19, 1932 10 Sheets-Sheet 1 1936' w. H. GRANT 2,028,151

METHOD OF CORRUGATING TUBES Original Filed April 19, 1932 10 Sheets-Sheet 2 21, 1936- w. H. GRANT 1 METHOD OF CORRUGATING TUBES Original Filed April 19, 1952 10 shqets-sheet 3 U /50 U 0/ I 'wZZ/am Z7 67%??? WYMI Jan. 21, I H G T METHOD OF CORRUGATING TUBES Original Filed April 19, 1932 10 Sheets-Sheet 4 Jan,- 1936- GRANT mmnon or coRRuGATINe TUBES Original Filed April 19. 1952 10 Sheetse1. 6

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1936- w. H. GRANT METHOD OF CORRUGATING TUBES Original Filed April 19, 1932 10 SheetsSheet 7 Jan. 21, H. GRANT rmuon OF CORRUGATING mans ori inal Filed April 19, 1932 10 Sheets-Sheet 8 4 I 1 I I 1 A w. H. GRANT 2,028,151

' METHOD OF CORRUGATING TUBES Original Filed April 19, 1932 10 Sheets-Sheet 9 Patented Jan. 21, 1936 UNITED STATES PATENT OFFICE 2,028,151 METHOD OF CORBUGATTNG TUBES William H. omit, Cleveland,

Ohio, assignor to The Bishop & Babcock Manufacturing .Com-

pany, Cleveland, Ohio, a' corporation of Ohio 6 Claims.

This invention relates to metallic bellows such as are used in thermostats and for analogous purposes, and has to do with a method of corrugating tubular metal blanks to produce bellows of the character stated.

It is an object of my'invention to provide a method of corrugating tubular metal blanks by subjecting the blank to internal pressure andto axial pressure, while positioned between spaced mold sections extending about the blank, whereby the blank is expanded radially between the mold sections and is compressed axially so as to produce the desired corrugations. Further objects and advantages of my invention will appear from the detailed description.

In the drawings:

Figure 1 is a semi-diagrammatic view of a. tubecorrugating machine suitable for practicing the method of my invention, and the auxiliary mechanisms used therewith, the machine proper being shown in elevation;

' Figure 2 is a front view of the machine;

Figure 3 is a side view of the machine;

Figure 4 is a front view of the machine on an enlarged scale, partly broken away and in section, parts being shown in elevation;

Figure 5 is a sectional view taken vertically through the die assembly and associated parts,

parts being shown in elevation;

Figure 6 is a section taken substantially on line 6-6 of Figure 5;

Figure I is an elevation of the die assembly and.

partly broken away and in secstep of the method of associated parts, tion, illustrating the first my invention;

Figure 8 is a view similar to Figure 'l illustrating the final step in the corrugating of the tube in accordance with my method;

Figure 9 is a front view of thevalve block;

Figure 10 is a section taken substantially on line Iii-l0 of Figure 9;

Figure 11 is a section line ll-Il of Figure 9;

Figure 12 is a front and in section, illustrating a modified form of corrugating machine in which the parts are operated hydraulically;

Figure 13 is a vertical sectional view through 0 the pressure head and the pressure inlet tube, and

associated parts, illustrating a modification for I corrugating a tubular metal blank open at both ends and provided with end flanges;

Figure 14 is a plan view of the nut for securing 55 the upper end of the blank;

taken substantially on view, partly broken away (Cl. 153-'l3) Figure 15 is a plan view of the lowermost die section in the modified form illustrated in Figure 13.

This application is a division of my copending application for Means for corrugating tubes, Serial No. 606,117, filed April 19, 1932.

The machine comprises a rectangular frame I including a top plate 2, base 3, and side plates 4, all suitably secured together as by bolting or in any other suitable manner. Preferably the top plate 2 and base plate 3 are connected, at the front and back of the frame, by tie rods to which act as tension members to resist vertical stresses to which the frame is subjected. A rack bar 5 is slidably mounted in a bracket 6 bolted to base plate 3 at the under face thereof. A six-armed spider 1 seats upon the upper end of rack bar 5 and operates through an opening 8 in the base plate 3. This spider is provided with a central hub 9 from the lower end of which extends an opening conforming in size and shape to the upper end of the rack bar. Hub 9 is further provided with a reduced bore l0 extending from the upper end and axially thereof for reception of a stud ll disposed centrally of the lower face of a cylindrical pressure head I2. This head is provided, in its upper face, with a central depression I3 for reception of the lower end of a tubular metal blank to be corrugated, and with a relatively shallow recess l4 extending outwardly from the depression and conforming in width to the width of the desired corrugation of the blank. The rack bar is moved vertically by means of a spur pinion l5 meshing therewith, this pinion being secured upon a shaft it upon one end of which is secured an operating lever ll. when the lever I1 is in the raised position of Figure 3, the rack bar 5 is in lowered position and the spider I and pressure head I2 occupythe positions shown in Figure 5.

Top plate 2 is provided with a central collar l8 extending upwardly therefrom and disposed cenpressure head l2. A pressure inlet tube is extends through collar l8 and is secured therein, in endwise adjustment, by suitable nuts and 2| which screw onto the inlet tube l9 and bear against the under face of plate 2 and the upper end of collar l8, respectively. A head 22 screws onto the lower end of tube I9, this head being provided with a bore 23 aligned with bore 19a of tube IS, a gasket 24 being disposed between the head and the lower end of tube l9, about bores Na and 22. A Hanged nut 25 screws onto traily of the plate, this collar being coaxial with 1 a shoulder 26 adjacent the upper end of a reduced neck 21 extending from the lower end of head 22.

A clamping plug 28 is secured in head 22 by means of a reduced and threaded neck 29 which screws into an enlarged bore of the head, such bore forming a continuation of bore 23. Plug 28 is provided with a bore 3| extending from its lower end, from the upper end of which bore extends a reduced bore 32 aligned with bore 23 of the head. A suitable gasket 38 is disposed about the neck 29 and confined between the shoulder at theupper end of the plug and the adjacent un der face of head 2.2. Neck 21 of the head is suitablybored from its lower end to provide a down wardly flaring recess 33 from the upper end of which extends a cylindrical recess of slightly greater diameter than plug 28. The lower end of the plug is rounded to provide a nose element 34 which facilitates positioning of a tubular metallic blank 35 over the plug, the upper end portion of this blank being inserted between the plug and the surrounding wall of the cylindrical recess in neck 27. A clamping ring 36 of leather or other suitable friction material fits about blank 35 and into the flared recess 33, the outer face of this ring being inclined similarly to the surrounding wall of the recess. The flange 25a of nut 25 engages beneath ring 36 so that when the nut is screwed onto neck 21 ring 36 is forced into recess 33 so as to grip the blank tightly about plug 28. By slightly loosening nut 25, the compression of ring 36 is released sufliciently to permit of insertion or withdrawal of the upper portion of the blank between the plug 28 and ring 36, without necessity for complete removal of nut 25 from neck 21. This gripping of the blank about plug 28 also serves to provide a fluid tight and pressure resistant closure between the blank and the plug. While the blank 35 is pref: erably inserted into neck 21 of the head until the upper end of the blank contacts the under face of the head adjacent the gasket 39, this is not essential so long as the upper end portion of the blank is disposed between plug 29 and the clamping ring 36. The plug is providedwithducts 31 extending radially thereof and opening intobore 3|, nose element 34 being so shaped as to permit of air which might otherwise be trapped between the wall of the blank and the nose entering these ducts and thus escaping through the bores |9a and 23, 32 and 3|. The lower closed end of blank 35 seats in recess I3 of pressure head l2.

The blank 35 is disposed between die members 38 which are spaced apart lengthwise of the blank and encircle the latter. Each of these die members is provided with an annular recess 39 in each face and extending from the inner edge thereof, this recess conforming in depth to onehalf of the depth of a desired corrugation to be produced in the blank 35, and in width to the width of the desired corrugation. Flange 25a of nut 25 is also provided with arecess 48 corresponding to the recesses 39 of the die members. When flange 25a of nut 25 and the die members 38 and pressure head |2 are moved into contacting relation, the recesses thereof define die cavities corresponding in size and shape to the corrugations which it is desired to produce in the blank 35.

Each of the die members 38 comprises semicircular sections 38a which constitute a circular die. These dies decrease in diameter from the top die to the bottom die and are suitably mounted, as by tongue and groove means, in semi-circular holders 4| to which the die sections are pinned ers 4| normally rest. The remaining holders 4| are successively connected together for relative vertical sliding movement'in the same manner as the top holder is connected to the support 42, the screws for connecting the successive holders together preferably being offset relative to each other and to the screws which connect the top .holder 4| to the support. The holders for the dies are thus connected for relative vertical movement and are disposed in nested-relation. Preferably, each of the die sections 38, with the exception of the lowermost die section, is provided with a plurality of suitably disposed guide pins 46 slidable in suitable bores extending from the upper face of the holder for the next succeeding die section. These pins, though not essential, contribute to holding the die sections accurately in vertical alignment one with the other. The lowermost die ring is of relatively small diameter and requires no guiding means other than its associated holding ring. The pressure head |2 flts snugly within the ring of this lowermost die section so as to be guided thereby in the axial compressing of the tubular blank.

The supports 42 flt snugly into vertically grooved lugs 58 of cross-heads 5|, to which the supports are bolted or otherwise suitably secured. The cross-heads 5| are of arcuate cross section and of less than degrees in extent. These cross-heads are slidably mounted on the base plate 3 of the frame and are provided, at their under faces, with ribs or extensions which operate in guideways 52 of plate 3 (Figs. 4 to 7) for guiding the heads during movement thereof, in a known manner. ably secured in guideways 52, each of these members including a laterally and outwardly projecting stop block 55. Blocks 55 are so disposed that the transverse centers thereof are in the plane of the axis of pressure head I2 and the head 22 taken from front to back of frame 1 and perpendicular thereto. Screw studs 56 are adjustably secured by'jam nuts'5l in lugs 58 of each head 5|, at the front and the back thereof. These studs 56 provide adjustable means cooperating with the blocks 55 for assuring that the ends of the semi-circular die sections 38a and die holders 4| are accurately disposed in contacting relation when the heads have been moved into their extreme positions toward each other,

- while avoiding subjecting the die sections and holders to objectionable stresses by movement of the heads toward each other.

The holders 4| are provided, at the ends thereof, with guide studs 60 and with bores for reception of such studs. Preferably, the studs and bores at the ends of each of the two holders 4|, constituting a holding ring, are alternately related with a view to assuring greater accuracy in aligning of the holders. Each of the studs is preferably provided with a shoulder 6| which constitutes a spacing element of proper thickness to contact the ends of the holders 4|, which are thus slightly spaced apart when the adjacent ends of the die sections 38a are in accurate and close contact, but without the die sections being Stop members 54 are suit placed under objectionable pressure. I also preferably provide each of the die sections 660 with a guide pin 62 (Fig. 6) which engages into a corresponding bore in the adjacent end of'the other die section. These pins 62 are disposed outwardly beyond the recesses 36 and, preferably,

. one of the pins is carried by one of the die sectlons, the other pin being carried by the other die section. The die assembly construction illustrated and described assures that the die sections of the respective die rings will be accurately closed and disposed about the tubular blank when the cross-heads 6| occupy the position illustrated in Figure 6, while avoiding subjecting the die sections to objectionable stresses.

Each of the heads 6| is provided, at the outer side and centrally thereof, with an integral boss 66. This boss receives the rounded inner end portion 66a of a screw shaft 66 which threads through a flanged bushing 61 which extends through and is bolted to side member 6 of frame I. The outer end of bushing 61 fits into a flanged collar 66 bolted to member 6. A hand wheel 16 is suitably secured upon the outer end of shaft 66. Dog pointed screws 1| are suitably secured thru boss 66 and extend in front of a collar 12 on end portion 66a of shaft 66. A pressure disc 13, disposed in a recess 16 in the boss, is contacted by the rounded inner end of shaft 66. The shaft is thus connected to the cross-head for adjusting the latter toward and away from the center of frame I.

A valve block 16 is screwed or otherwise suitably secured upon the upper end of tube I6. Referring more particularly to Figures 9 to 11, inclusive,

neck 11 which screws upon the upper end of tube I I6. This passage 16 is intersected, adjacent each end thereof, by upper and lower passages 16 and 16, respectively. Passage 16 opens at its ends into valve chambers 66 and 6|, access to which may be had by means of suitable screw plugs 62 and 63, respectively. Valves 66 and 66 are disposed in the chambers, 86 and 6|, respectively. These valves are of similar construction and each valve seats in a thimble 66 which screws into the chamber and is shaped to provide a seat for the valve. The block is suitably bored coaxially with the valve chamber to accommodate stem 61 of the valve, this stem operating through a suitable stufling box structure 66 in a known manner. A flanged disc 66 is suitably secured upon the outer end of valve stem 61 and an expansion coil spring 66, disposed about the stuiflng box 66, is confined between this disc and a shoulder 6| of the stufflng box structure. This spring serves normally to hold the valve seated. Passage 16 opens into valve chambers 62 and 63 in which are located the valves 66 and 66, respectively, access to which may be had by means of screw plugs 66 and 61, respectively. of similar construction and operation. The upper end'of passage 16 is suitably bored and threaded at 16a for reception of a pet cook 66 of known type for a purpose to be later disclosed.

A suction pipe I66 communicates with valve chamber 6| below or in front of valve 66. This pipe I66 also communicates with a suitable source of suction, such as a suction pump I6I having driving connection with an electric motor I62 or other suitable source of power. By opening the valve 66 communication is established between the source of suction, by means of valve chamber 6|, passages 16 and 16, and the tube I6 under pressure,

this block is provided with a central- The valves are chamber 62 below or in front of valve 66. This pipe is connected to a suitable supply of water connected to the street main. A valve I66 of known type is provided in pipe I66 for controlling the flow of water therethrough. After the air has been exhausted from the tubular blank, this blank may be filled with water from pipe I66 by opening valve I66 and then openingvalve 66. Normally, valve I66 remains open, it only being necessary to open valve 66 to admit the water to the blank.

A pressure supply pipe I61 communicates with valve chamber" above or in back of valve. This pipe-communicates with the outlet of an acccumulator or equalizer I66 for supplying liquid under constant pressure to the pipe I61. Water is supplied to the accumulator by a pump I66 of suitable type, the outlet of which is connected by a pipe I I6 to the inlet of the accumulator. A suitable check valve I II is interposed in pipe I I6 and a pressure gauge 2 is connected to this 1 pipe between the pump outlet and the check valve.

The pump is driven by an electric motor H3 and the inlet of the pump is connected by a pipe I I6,

- in which is interposed a suitable valve II6, to a overflow pipe I23 communicates with tank 6' and with a relief valve structure I26 supported by a standard I25 and communicating at I26 with pipe I61. The valve structure I26 includes a loaded relief valve normally held closed by a lever I21 pivoted at I26, a weight I26 being adjustably mounted on this lever. Under normal conditions, the relief valve remains closed, but if the pressure in pipe I61 exceeds a predetermined maximum, the relief valve is opened and the water or other incompressible fluid thus released is returned by pipe I23 to the tank 6. A suitable control valve I36 is disposed in pipe I61 and placed so as to be readily accessible to' the operator of the machine.

The accumulator I66 is of known type and comprises a cylinder I3I in which operates a piston I32, this piston having mounted at the upper end thereof a multiple armed head I3'3 from which suitable weights I36 are suspended by means of rods I36. Water or other suitable incompressible fluid pumped into the cylinder I3| forces the piston I32 upwardly and is placed under constant pressure by the weight I36 and associated parts. The accumulator thus provides a source of supply of liquid under substantially constant and predetermined pressure, which liquid may be admitted to the tubular blank by opening the valve 66. It is to be noted that when valve 66 is opened, the resulting pressure in the passages and valve members of the block 16 acts such as the ordinary water pipe to hold the other valves of this block seated or with the position of head I33 of the acccumulator. Two arms I40 and I4I are pivotally mountedat one end on a bracket I42. Arm I4 Isupports for movement therewith a mercury tube switch I43 of known type which is interposed in the circuit of motor II3. A rod I44 connects the arms I40 and MI for similar movement. A trip finger I45 pro jects from arm I33a of head I33 and is disposed to contact the arms I40 and I. This finger is suitably disposed and shaped to pass by each arm after actuation thereof. As the head I33 approaches the limit of its upward movement, finer I45 contacts arm MI and rocks it into the dotted line position of Figure 1, thus rocking this arm and tilting the switch I43 into circuit opening position, indicated by dotted lines, after which the finger may pass beyond arm I. This opens the circuit of motor I I3, thus throwing the pump I09 out of operation and eliminating possibility of injury to the accumulator such as might result from continued operation of the pump when piston I32 has been moved into its uppermost position, particularly if the relief valve of structure I24 failed to open for any reason at the pressure for which it is set. The pump remains out of operation until piston I32 of the accumulator moves downwardly to a predetermined extent, at which time finger I45 actuates arm I40 so as to rock arm HI and switch I43 into circuit closing position, thus setting the pump into operation. Arm I40 is preferably of proper length to clear the finger I45 as it passes downwardly beyond this arm after the latter has been rocked into the full line position of Figure 1. This provides an automatic control for throwing the pump I09 into and out of operation, as conditions require, and to maintain the proper supply of water or other liquid to the accumulator, the pump being operated intermittently.

A bracket I50 is suitably secured to the front of top plate 2 of the frame I for vertical adjustment, as by bolt and slot means I5I. This bracket rotatably supports a tubular shaft I52 to which an operating lever I53 is secured by a set screw I54, or in any other suitable manner. A two-armed member 155 is suitably secured on shaft I52 for movement therewith, as by means of a set screw I56. A shaft I51 is rockably mounted through the tubular shaft I52. An operating lever I 58 is suitably secured upon one end of shaft I51, as by means of a set screw I59. A twoarmed member I60 is secured upon the other end of shaft I51 by means of a set screw I6I. The bracket I50 is provided with forwardly projecting bosses I62 which are suitably bored for reception of plungers I63, the forward portions of which are rounded as shown in Figure 3. These plungers are urged forwardly by expansion coil springs I64 disposed about the stems I65 of the plungers and confined between the heads of the latter and the inner ends of the bosses. The stems I65 of the plungers are disposed coaxially with the stems 81 of the valves in the blocks 15, the rearward ends of plungers I65 being in close proximity to the forward ends ofthe valve stems. Upon rearward movement of any of the plungers I63 the corresponding valve of the block 15 is opened, and upon release of the plunger this valve is returned to seated or closed position.

Preferably, I provide a gauge I10 of suitable type for indicating the pressure in passage 16 of the block and in the tubular blank. This gauge is conveniently of proper type to indicate pressure above atmospheric produced bythe liquid suppliedunder pressure from pipe I01, and to indicate also pressure belowatmospherlc to indicate the degree of partial vacuum produced by the suction means. The gauge I10 is connected by a tube I 1| to a passage I12 bored in the block 15 from one side thereof and intersecting the passage 16.

' In the use of the machine, the cross-heads I are moved outwardly into positions adjacent the sides of frame I so as to give ready access to pressure head I2 and clamping head 22 and associated parts. The pressure head I2 may be moved downward y beyond its normal position shown in Figure 5, by raising the lever I1, after which the upper end portion of the blank 35 is secured in the clamping head 22 in the manner previously described. Lever I1 is then moved downwardly'slightly so as to raise the pressure head I2 into position such that the lower end of the blank seats in the depression I3. The crossheads 5I are then movedinwardly toward each other into their innermost position, thus disposing the die rings 38 about the blank 35 as in Figure 5. The tubular blank 35 is now in position to be corrugated, with the die assembly closed and the die members or rings disposed about the blank in operative relation thereto and so as to encircle completely the blank.

With the blank in position and the die assembly closed, the operator first depresses lever I 53, thus opening valve 85, which may be termed the suction valve, and connecting the interior of the bla'nlfto the suction pump IOI. This pump acts to exhaust the greater portion of the air from the tubular blank as well as the passages and spaces of the valve block and tube I9 and associated parts, within a short time. It should be here noted that the pet-cock 98 is normally closed. The operator then swings lever I53 upwardly, thus closing suction valve 85 and opening valve 94, which may be termed the supply valve, admitting water or other suitable liquid through pipe I 05 and the passages of the block and of tube I9 and associated parts into the tubular blank 35. This blank and the various passages and spaces communicating therewith are thus quickly filled with water. The pet-cock 98 forms convenient means for indicating when the blank and the passages of the valve block and associated parts have been completely filled with water, which may readily be determined by opening the petcock briefly. This pet-cock also provides means for releasing any small volume of air which may be trapped in the upper portion of passage 16. Lever I53 is then released, thus closing the supply valve 04. The operator then opens valve I30, ifthis valve is closed, and then depresses lever I58 opening the valve 84 which may be termed the high pressure valve. This admits the liquid or incompressible fluid from pipe I01 into the passages of the valve block and thence into the tubular blank 35. The weights I34 of the accumulator I08 are of such value thatthe pressure within the blank 35, when the valve 84 is opened, is of proper value to bulge the blank 35 outwardly slightly between the die rings and pressure head I2 and flange 25a of nut 25, as in Figure 7. The operator then swings lever I1 downwardly, while holding the lever I58 depressed so as to maintain the pressure within the tubular blank. This raises the spider 1 and the pressure head I2, thus subjecting the blank 35 to endwise pressure so as to compress it axially while subjected to internal pressure. As the head I2 moves upwardly; the metal of the blank which is displaced by the" axial compression thereof is redistributed outwardly rings and head as in Figure 8.

, e y a 2,028,161 and nann of the blank between the die rings.

and these rings are successively raised by contact of the arms of spiders I. with the holders 4|, the

arms ofthe spider moving upwardly between the supports 42. As the pressure head I! reaches its p rmost position, into contact with one another, the upper face of the top die ring contacting'the under face of flange 28a of nut 25 and the upper face of head I! contacting the under face of the lowermost die ring. The corrugations of the tube are thus shaped to conform to the recesses defined by the i2 and the flange 2500f nut 25, The water or other liquid displaced by the axial compression of the tube is forced through the pipe llll into the accumulator I08. If the pressure rises beyond thepredetermined maximum during the axial compression of the tubular blank, the relief valve opens and the excesswater is returned through pipe I28 to tank H8. After the blank has been thus corrugated, the operator raises lever I58, thus closing the pressure valve 84 and opening the relief valve 95. This serves to relieve any pressure which might otherwise exist within the corrugated tube 85 due to the presence of air pockets or other causes,

and any water displaced when the valve 95 is opened, is returned totank. I I6 through pipe' I22. The cross-heads are then moved away from each other so as to withdraw the sections of the between the corrugations of the II is raised so as to lower die rings from tube 35, and the lever the pressure clamping nut 25 the corrugated tube may now be withdrawn therefrom and replaced by' another tubular blank to be corrugated. when the sections of the die rings arewithdrawn from the corrugations of the corrugated tube, these sections and the holders therefor return by gravity to their normal positions shown in Figure 5.

Since the holders ll are free for relative sliding movement, the die rings 88 are free for relative movement. of the blank between these rings, as in Fig. '7, the rings 88 have slight relative movement one toward the other to accommodate shortening of the blank incident to bulging thereof. This is advantageous in that it prevents objectionable thinning of the wall of the blank, such as would occur if the die rings were held against relative movement toward one another. The blank, after the preliminary bulging thereof, is in substantially the form shown in Fig. 7 and may be considered as comprising a plurality of contiguous segments each of which is arched but slightly lengthwise of the blank and offers considerable resistance to endwise compression thereof. In the upward movement of the rack bar 5 head I! subjects the blank to endwise pressure applied directly to the lower end of the blank. The total resistance of the slightly bulged segments of theblank above the lowermost die ring 88, to endwise compression of the blank, is much greater than the resistance of the single lowermost segment between head I! and the lowermost ring 88, and this lowermost segment is subjected to direct and positive pressure by the head. of the bulged blank offers considerably less resistance than the remaining segments, the metal of this lowermost segment will flow radially between head I! and the lowermost ring 88 until the head the die rings are brought head l2. By slightly loosening the During the preliminary bulging.

Since the lowermost segment- When the lowermost corrugation has thus been formed to final size and shape, the arms of spider I contact the lower edge of holder ll of the second die ring 38, thus subjecting the second segment of the bulged blank to direct and positive pressure and forming it to final size and shape in the same manner as the lowermost segment was formed to final size and shape. In the continued upward travel of rack bar 5 the arms of spider I contact the holders ll successively so as to move the die rings 88 successively one toward the other and thus successively form the segments of the bulged blank to the final size and shape of the corrugations of the bellows being produced. with respect, to formingof the next to the top corrugation, it is pointed out that the pressure to which the corresponding segment of the bulged blank is subjected is direct and positive and, therefore, has considerably greater effect on this segment than on the top segment of the bulged blank, with the result that the next to the top corrugation is formed accurately to the final shape the top corrugation is formed accurately to final size and shape between the'top die ring and the nut 25.

The floating mounting of the die rings 38 has the further advantage that it accommodates any lack of uniformity in the preliminary bulging of the blank between the rings, due to slight differences in wall thickness or temper of diiferent portions of the blank. In practice, it is difiicult to produce a tubular blank of absolutely uniform temper and wall thickness, and portions of the blank are apt to differ in these respects. These differences exist, though they may at times be difficult to detect, and must be taken into account in producing the bellows, if maximum efiiciency is to be attained. The floating mounting of the rings compensates for lack of uniformity in the blank and avoids objectionable stretching of the wall thereof.

When the bulged blank is subjected to endwise pressure in theforming of any one of the segments thereof to the final size and shape of the corrugations of the bellows being produced, other segments of the blank may be more or less extended radially with corresponding relative movement one toward the other of the corresponding die rings, depending upon the wall thickness of the blank and other factors. However, the segments of the bulged blank will be successively and individually formed to the final size and shape of the corrugations of the bellows being produced, in the manner above stated, which assures accuracy and uniformity of the corrugations in the bellows, and such radial extension of the segments of the bulged blank prior to forming thereof to the final size and shape of the desired corrugations is not objectionable and does not interfere with the desired precision of the corrugations finally produced. A further advantage of forming the bellows in this manner is that the production of the bellows may be performed as a continuous operation, and the power required to perform this operation is materially less than would be required if it were attempted to form all of the corrugations to final shape and size simultaneously.

Referring to Figs. 5 and 7, it will be noted that the dies are disposed in spaced relation and are, in effect, clamped around the blank by. the radial bulging thereof. Each die is attached to an associated'holder ll, the die and the holder together possessing appreciable weight. The crnbined weights of the dies and their associated holders,

beyond any given die with the holder of which spider 1 contacts in the travel of the ram, will resist axial compression of the blank, and this resistance will increase in accordance with the number of dies and associated holders beyond the head I2. Accordingly, the bulge or segment of the blank between the die carried by the holder with which spider 1 contacts and the next adjacent die normally offers least resistance to radial extension and will be formed to final size and shape before any of the other corrugations of the blank. The weight of the dies and the holders is a factor which supplments the resistance of the bulges of the blank to axial compression of the latter, and cooperates therewith to assure the forming of the corrugations of the bellows to final size and shape successively and individually.

The corrugations of the bellows are not necessarily in all instances formed to final size and shape both successively and consecutively, though this is the general tendency and should usually occur. In some instances, however, it may happen that a bulge in the blank will be formed to a corrugation of final size and shape before another bulge nearer the head I2. This may be accounted for by the fact, previously referred to, that the temper, wall thickness or grain structure of the portion of the blank defining that particular bulge is such as to offer appreciably less resistance to axial compression and radial extension than any other bulge nearer the end of the blank subjected to pressure by the ram. For example, referring to Fig. '1, it may happen that the bulge of the blank between the second and third dies from the head I2 offers relatively little resistance to axial compression and radial extension. In the travel of the ram toward head 22, the bulge between head I2 and the first or lowermost die may be formed first, to a corrugation of final size and shape, the bulge between the second and third dies may be next formed to a corrugation of final size and shape, due to its relatively slight resistance to axial compression and radial extension, the bulge between the first and second dies being formed to a corrugation of final size and shape after the bulge between the second and third dies. However, the bulges of the blank are formed to corrugations of final size and shape individually and successively, and the general tendency is for them to be formed to final size and shape both successively and consecutively.

While the above is thought to be a correct explanation of the causes for the bulges of the blank being formed individually and successively to corrugations of final size and shape in the manner stated, it is appreciated that there may possibly be other factors not apparent which afiect the result obtained. However, the above stated theory of operation is believed to be, in the main at least, correct, and the corrugations are formed to final size and shape successively, as stated.

The water supply pipe I05 and associated parts, for supplying water to the tubular blank, are preferably provided but are not essential. The advantage of this water supply means is that it avoids the necessity of frequently replenishing the supply of water in tank II8. It will be understood, however, that the entire supply of water for filling the tubular blank and subjecting it to internal pressure may be had through the pipe I01, if desired. Also, if desired, the tubular blank and associated passages of the valve block and associated parts may be filled by pouring water through a suitable nipple or equivalent member secured in the upper end of passage 16 in place of the pet-cock so. ,Also, the provision of the suction pump IN and the suction valve and associated parts is not essential, though preferred.

WhileI preferably apply the bulging internal I pressure to the tubular blank before subjecting it to endwise pressure, this is not essential, and both the internal pressure and the endwise pressure may be applied to the blank simultaneously if de-.

sired.

In the modified form illustrated in Figure 12, the cross-heads 5| and the spider 1 and the pressure head I2 are operated by hydraulic means. Cylinders I15 are mounted upon side members 4 of frame I. Pistons I16 operate in these cylinders, these pistons being carried by piston rods I11 which operate through stuifing boxes I18, the inner ends of these rods being pinned at I19 to bosses 85 of the cross-heads. Communicating tubes I80 communicate with cylinders I15 through the outer ends thereof, and a tube I8I communicates with the inner ends of the cylinders I15. Pressure for operating the pistons I18 is supplied through a pipe I82 which communicates with the casing of a suitable four-way valve I83, a relief pipe I84 also communicating with the casing of this valve. When the valve is turned into one position, the tubes I80 are connected to the supply of water or other liquid under pressure so as to force the pistons I16 inwardly of the cylinders I15, tube I8I being connected to the relief pipe I84 so as to permit escape of water from in front of the pistons I16. When the position of valve I83 is reversed, tube I8I is connected to the supply of liquid under pressure and tubes I80 are connected to the relief pipe for moving the pistons I16 outwardly and retracting the crossheads 5I.

A cylinder I85 is bolted to the under face of base plate 3 of the frame. A piston I88 operates in this cylinder and is provided with an adjustable stop I81 which contacts the lower head of the cylinder to limit downward movement of the piston. Piston rod I88 operates through a stufling box I89 and spider 1 is of piston rod I88, at I90. A tube I9I communicates with the upper end of cylinder I85 and with a valve casing I92 In which is mounted a four way valve I93 of known type. A pressure supply 'pipe I94 also communicates with the valve casing, as does a relief pipe I95. A tube I88 communicates with cylinder J85 through the lower end thereof and with valve casing I92. By proper manipulation of valve I93, piston I86 and piston rod I88 may be raised and lowered under pressure as required.

With the exception of the hydraulic means for operating the cross-heads 5I and the spider 1 and pressure head I2, the construction and operation of the machine of Figure 12 is similar to that of the machine of Figures 1 to 11, inclusive, and need not be further described.

The machine so far described is adapted for corrugating a tubular metal blank closed at one end. In Figures 13 to 15, I have illustrated a slight modification of the tube mounting and securing means by means of which the machine is adapted for corrugating metal blanks open at both ends. In Figure 13 the pressure inlet tube I8!) is provided, at its lower end, with a reduced neck I80, which is threaded for reception of a fianged nut 200. This nut is formed in two sections 200a and 200b which are hinged together at 20I. Section 200a is provided with a slotted lug 202 for reception of a swing bolt 203 pivoted at 204 in a slotted lug 205 formed integrally with pinned on the upper end section 2110b. A wing nut 205 screws onto bolt 203 and contacts lug 2M for releasably securing the two sections of the nut together. A disc 201 is suitably secured, as by means of screws 208 to the upper face of pressure head l2b. The disc 20'! is formed in two sections 201a of semi-circular shape, each section having a recess 209 correspor. ing to the recess of the head l2 of Figure 5. Flange 200a of nut 200 is provided in its under face with a recess 40a corresponding to recess 40 of the nut 25 of Figure 5. This flange 200a is adapted to engage beneath a flange 35b at the upper end of a tubular blank 35a, this blank being open at its lower end and provided at such end with a second flange 351). A gasket 2H1 is disposed between flange 35b at the upper end of the blank 35a and the under face of extension I90 of tube l9b. The nut serves to clamp the blank 35a tightly in position and, in conjunction with gasket 2|0, to provide a fluid tight and pressure resistant closure between the upper end of the blank and the lower end of the extension I90. Sections 201a of disc 201 seat upon the upper face of flange 35b at the lower end of blank 35a, and a gasket 2 is interposed between this flange and the upper face of pressure head I212. The sections 201a of disc 201 completely encircle the blank 35a and are pressed tightly down against flange 35b by means of the screws 208 so as to anchor securely the lower end of blank 35a and provide a fluid tight and pressure resistant closure between the flange 35b and head l2b. This provides simple and highly efiicient means for eifectively securing the ends of a tubular blank which is open at both ends. I do not, however, limit myself to the particular securing means shown,

since various other means may be employed for securingthe ends of the blank and providing fluid tight and pressure resistant closures therewith, as will be understood by those skilled in the art.

What I claim is:

1. The method of producing metal bellows, which comprises first subjecting a tubular metal blank to internal pressure only while disposed within spaced die rings and of proper value to bulge the blank radially and outwardly between the rings while permitting relative movement of said rings one toward the other to accommodate shortening of the blank to compensate for the radial extension thereof, and then compressing the blank axially and further extending it radially while positively moving the rings one toward the other, thereby forming a corrugation in the blank, as a continuous operation.

.2. The method of producing metal bellows, which comprises disposing a tubular metal blank in cooperating relation to spaced die rings extending about the blank, subjecting the blank to internal pressure in the absence of endwise pressure and of proper value to bulge the blank radially and outwardly between the rings while permitting relative movement of said rings onev toward the other to accommodate shortening of the blank to compensate for the radial extension one toward the other, thereby forming, corrugathereof, and then compressing the blank axially and positively moving the rings one toward the other at a rate commensurate with the axial compression of the blank, while maintaining the pressure within the blank, and thereby further ex- 5 tending the blank radially between the rings and forming a corrugation in the blank, as a continuous operation.

3. The method. of producing metal bellows, which comprises first subjecting atubular metal 10 blank to internal pressure only while disposed within spaced die rings and of proper value to bulge the blank radially and outwardly between the rings while permitting relative movement of said rings one toward the other to accommodate shortening of the blank to compensate for the radial extension thereof, and then compressing the blank axially to displace the metal thereof and redistributing the displaced mctaloutwardly and radially of the blank between the rings while causing movement of the rings toward each other, thereby forming a corrugation in the blank.

-4. The method of producing metal bellows, which comprises subjecting a tubular metal blank to internal pressure and to axialpressure while disposed within spaced die rings, thereby compressing the blank axially and extending it outwardly and radially between the rings, and thereafter positively and successively moving the rings tions in the blank, as a continuous operation.

5. The method of producing metal bellows, which comprises disposing a tubular metal blank in cooperating relation to a plurality of die rings free for relative movement lengthwise of the blank, subjecting the blank to internal pressure and thereby extending it radially between the die rings while imparting relative movement to said rings toward each other in accordance with and to accommodate shortening of the blank to compensate for the radial extension thereof, thereby forming preliminary corrugations in the blank, and thereafter positively and successively moving the rings one toward the other and thereby successively forming the preliminary corrugations to final size and shape, as a continuous operation.

6. The method of producing metal bellows, which comprises disposing a tubular metal blank in cooperating relation to a plurality of die rings free for relative movement lengthwise of the blank, subjecting the blank to internal pressure and thereby extending it radially between the die rings while imparting relative movement to said rings toward each other in accordance with and to accommodate shortening of the blank to com- 55 pensate for the radial extension thereof, thereby forming preliminary corrugations in the blank,

and thereafter positively and successively moving the rings-one toward theother while compressing the blank axially and thereby successively form- 0 ing the preliminary corrugations to final size and shape, as a continuous operation.

WILLIAM H. GRANT. 

